What it is
The Indian Computing Olympiad (ICO) is India’s route to the International Olympiad in Informatics (IOI), the world’s leading programming contest for school students. It is run by the Indian Association for Research in Computing Science (IARCS). People often search for its rounds by name: ZIO, ZCO and INOI.
Informatics olympiads are about algorithms: finding a clever, efficient way to solve a problem, then (from the second round) writing a program that does it correctly and fast enough. Knowing a programming language is only the starting point. The real skill is problem solving.
Who can take it
ICO is open to all school students in India, from any school board. IARCS sets no lower age limit, so a younger student who is ready may take part. Students who have already finished Class 12 are not eligible. IARCS publishes the exact rules each year, including the academic year that counts, so check the official eligibility rules on the ICO site before registering. The other official routes, in maths and the sciences, are listed on the olympiads hub.
The stages
| Stage | Who | What happens |
|---|---|---|
| ZIO | Any eligible school student | Zonal Informatics Olympiad: problems worked out on paper, final answers entered at a test centre |
| ZCO | Any eligible school student | Zonal Computing Olympiad: a programming exam at a test centre, in C++, Java or Python |
| INOI | Students who qualify through ZIO or ZCO | Indian National Olympiad in Informatics: a programming exam in C++ only |
| IOITC | About 30 students from INOI | The IOI Training Camp, where the team is selected |
| IOI | India’s team of four | The International Olympiad in Informatics |
The first round has two parts, and a student can write ZIO, ZCO or both. Qualifying through either one is enough for INOI. This makes ZIO a good way in for students who are strong at mathematical and logical problem solving but new to coding, while ZCO suits students who already program.
India also takes part in the Asia-Pacific Informatics Olympiad (APIO) and the European Girls’ Olympiad in Informatics (EGOI). For APIO 2026, IARCS invited INOI medallists and the students selected for the training camp. IARCS announces how students are chosen for these contests each year.
When it happens
Registration for a new ICO cycle opens a few weeks before ZIO; for the 2026–27 cycle it opened in October. Students register individually online, and IARCS also accepts group registrations. ZIO has been held in November or December in recent cycles, at centres across India. ZCO dates have varied more, falling anywhere from December to April in recent cycles, and INOI follows ZCO. The training camp has been held in June in recent years, and the IOI after that. The ICO site’s announcements page is the place for this year’s dates, so check it regularly through the season.
How to prepare
- Start with IARCS’s own material. The ICO site has online study material, and its Basic Topics list is the syllabus for ZIO.
- Solve past problems. Past ZIO, ZCO and INOI problems are available, and IARCS’s problems archive lets you submit solutions to past problems and check them.
- Learn C++ in time for INOI. ZCO allows C++, Java or Python, but INOI allows only C++, so students heading for the second round should be comfortable with it well before.
- Study the classic ideas: sorting and searching, recursion, greedy methods, dynamic programming and graphs. The IOI’s published syllabus shows what lies ahead.
- Practise under time limits. Contest problems reward a correct, efficient idea more than polished code.
IARCS also lists a mentoring programme for ZCO, INOI and IOITC run by past training camp students. Be realistic: INOI and the camp are very demanding, and the IOI team has only four places. Even so, the problem-solving habits built along the way are valuable for any later study in computing or mathematics.
Where daily practice fits
ICO problems need long, focused sessions with a pen or an editor, and a daily quiz is no substitute. Ado is a free daily quiz of 8 questions, including a 60-second sprint, in maths, science, English, GK and reasoning, ranked only against students the same age. Its maths and reasoning questions can keep logical thinking warm on busy school days, and its Ado Rank builds from a student’s top three subjects and never resets. The algorithmic work still happens on its own.